R help - Aug 2005 - Converting characters to numbers in data frames

I'm sure I'm missing something obvious here, but I can't find the 
solution (including in the FAQ etc.).

I have a vector of names of variables like this: NRes.x.y. where x and y 
are numbers.  I want to extract these numbers as numbers to use 
elsewhere.  I can extract the numbers as a list of characters using 
strsplit(), and convert that to a data frame, e.g.:

NAMES=c("NRes.1.2.", "NRes.1.3.", "NRes.1.4.",
"NRes.1.5.", "NRes.1.6.")
NUMBERS=strsplit(gsub("NRes.","", NAMES, perl =T),
'.', fixed = TRUE)
NUMBERS.df=t(data.frame(NUMBERS))

But I now want to convert the characters to be numeric.  Using 
as.numeric(NUMBERS.df) converts them, but to a vector.  How can I 
convert and keep as a data frame?  I could use this:

matrix(as.numeric(NUMBERS.df), ncol=dim(NUMBERS.df)[2])

but I seem to be jumping through far too many hoops: there must be an 
easier way.  An suggestions?

Bob

-- 
Bob O'Hara
Department of Mathematics and Statistics
P.O. Box 68 (Gustaf H??llstr??min katu 2b)
FIN-00014 University of Helsinki
Finland

Telephone: +358-9-191 51479
Mobile: +358 50 599 0540
Fax:  +358-9-191 51400
WWW:  http://www.RNI.Helsinki.FI/~boh/
Journal of Negative Results - EEB: www.jnr-eeb.org

Anon. wrote:
> I'm sure I'm missing something obvious here, but I can't find
the
> solution (including in the FAQ etc.).
> 
> I have a vector of names of variables like this: NRes.x.y. where x and y 
> are numbers.  I want to extract these numbers as numbers to use 
> elsewhere.  I can extract the numbers as a list of characters using 
> strsplit(), and convert that to a data frame, e.g.:
> 
> NAMES=c("NRes.1.2.", "NRes.1.3.",
"NRes.1.4.", "NRes.1.5.", "NRes.1.6.")
> NUMBERS=strsplit(gsub("NRes.","", NAMES, perl =T),
'.', fixed = TRUE)
> NUMBERS.df=t(data.frame(NUMBERS))
> 
> But I now want to convert the characters to be numeric.  Using 
> as.numeric(NUMBERS.df) converts them, but to a vector.  How can I 
> convert and keep as a data frame?  I could use this:
> 
> matrix(as.numeric(NUMBERS.df), ncol=dim(NUMBERS.df)[2])
> 
> but I seem to be jumping through far too many hoops: there must be an 
> easier way.  An suggestions?
> 
> Bob
> 

How about this?

NUMBERS <- lapply(strsplit(NAMES, "\\."), "[", -1)
as.data.frame(do.call("rbind", lapply(NUMBERS, as.numeric)))

--sundar

Try:

NAMES=c("NRes.1.2.", "NRes.1.3.", "NRes.1.4.",
"NRes.1.5.", "NRes.1.6.")
pattern<-"NRes\.([0-9]*)\.([0-9]*)\."
data.frame(x=sub(pattern,"\\1",NAMES),y=sub(pattern,"\\2",NAMES))

@
output-start
Thu Aug 25 14:08:50 2005
  x y
1 1 2
2 1 3
3 1 4
4 1 5
5 1 6
output-end

Peter Wolf

Anon. wrote:
>I'm sure I'm missing something obvious here, but I can't find
the
>solution (including in the FAQ etc.).
>
>I have a vector of names of variables like this: NRes.x.y. where x and y 
>are numbers.  I want to extract these numbers as numbers to use 
>elsewhere.  I can extract the numbers as a list of characters using 
>strsplit(), and convert that to a data frame, e.g.:
>
>NAMES=c("NRes.1.2.", "NRes.1.3.", "NRes.1.4.",
"NRes.1.5.", "NRes.1.6.")
>NUMBERS=strsplit(gsub("NRes.","", NAMES, perl =T),
'.', fixed = TRUE)
>NUMBERS.df=t(data.frame(NUMBERS))
>
>But I now want to convert the characters to be numeric.  Using 
>as.numeric(NUMBERS.df) converts them, but to a vector.  How can I 
>convert and keep as a data frame?  I could use this:
>
>matrix(as.numeric(NUMBERS.df), ncol=dim(NUMBERS.df)[2])
>
>but I seem to be jumping through far too many hoops: there must be an 
>easier way.  An suggestions?
>
>Bob
>
>

On 8/25/05, Anon. <bob.ohara at helsinki.fi>
wrote:
> I'm sure I'm missing something obvious here, but I can't find
the
> solution (including in the FAQ etc.).
> 
> I have a vector of names of variables like this: NRes.x.y. where x and y
> are numbers.  I want to extract these numbers as numbers to use
> elsewhere.  I can extract the numbers as a list of characters using
> strsplit(), and convert that to a data frame, e.g.:
> 
> NAMES=c("NRes.1.2.", "NRes.1.3.",
"NRes.1.4.", "NRes.1.5.", "NRes.1.6.")
> NUMBERS=strsplit(gsub("NRes.","", NAMES, perl =T),
'.', fixed = TRUE)
> NUMBERS.df=t(data.frame(NUMBERS))
> 
> But I now want to convert the characters to be numeric.  Using
> as.numeric(NUMBERS.df) converts them, but to a vector.  How can I
> convert and keep as a data frame?  I could use this:
> 
> matrix(as.numeric(NUMBERS.df), ncol=dim(NUMBERS.df)[2])
> 
> but I seem to be jumping through far too many hoops: there must be an
> easier way.  An suggestions?

Try this:

   read.table(textConnection(NAMES), sep = ".")[,2:3]

You may also want to add the col.names= argument to the read.table call
if you want prettier column names.  Also I think Names and Numbers would
be sufficient to distinguish them from potential lower case counterparts.